# What happens if you put a drone on hover in a moving car

Gold Member
I was flying my drone last week and then it hit me. What happens to the drone if you put it in hover mode in a moving car? It must be a closed roof car and can move at any speed. But what my question is, what will happen to the drone? In hover mode, a drone will just float where it is. But if it’s in a moving car, would it move with the car? Remember, it’s still in hover mode. I was thinking that the drone would move back if the car were to go forward. Or at least it would appear to go back but isn’t it staying where it was told to hover? Anyway, will a hovering drone move with the car or will it stay where it was and the car and everything in it will just move with the car? Thanks so much if you could answer my (as usual) maybe confusing and analytical questions.

Related Other Physics Topics News on Phys.org
Drakkith
Staff Emeritus
The drone will tend to stay along a straight path (with respect to the ground) while hovering, so any acceleration, either from speeding up, braking, or turning, will cause the drone to move with respect to the car. So if you turn left, the drone will move towards the right side of the car, and if you brake the drone will move forwards under its own momentum. Here's a youtube video of a few guys flying a drone inside an RV. Notice how the drone tends to go the opposite way as the RV turns, requiring correction by the drone operator to avoid a crash.

lekh2003
ZapperZ
Staff Emeritus
I was flying my drone last week and then it hit me. What happens to the drone if you put it in hover mode in a moving car? It must be a closed roof car and can move at any speed. But what my question is, what will happen to the drone? In hover mode, a drone will just float where it is. But if it’s in a moving car, would it move with the car? Remember, it’s still in hover mode. I was thinking that the drone would move back if the car were to go forward. Or at least it would appear to go back but isn’t it staying where it was told to hover? Anyway, will a hovering drone move with the car or will it stay where it was and the car and everything in it will just move with the car? Thanks so much if you could answer my (as usual) maybe confusing and analytical questions.
In case you forget, according to an observer on Jupiter (or any other celestial body), the earth is moving! So when you have your drone in hover mode, what do you think that other observer sees?

Zz.

Gold Member
In case you forget, according to an observer on Jupiter (or any other celestial body), the earth is moving! So when you have your drone in hover mode, what do you think that other observer sees?

Zz.
The drone would be moving with the car? I’m so confused still

Nugatory
Mentor
Anyway, will a hovering drone move with the car or will it stay where it was and the car and everything in it will just move with the car? Thanks so much if you could answer my (as usual) maybe confusing and analytical questions.
In "hover mode" is the drone trying to stay still relative to the air around it, or trying to maintain a constant GPS position? That's a rhetorical question of course, but if you think about how the drone would behave under either definition of "hovering" and remember that the air inside the car is moving along with the car, it will all make sense.

CWatters and russ_watters
lekh2003
Gold Member
The drone tries to keep it's own inertia. When it is moving in a car, it is not stand still. It is moving at the speed of the car.

When you put it in hover mode, it will also keep it's inertia unless the car experiences acceleration (braking, change in direction).

When you jump up into the air, you don't suddenly stop moving and the Earth just rushes under you. You maintain your inertia.

olivermsun
It really depends how the drone's navigation system determines "hover." If it keeps the same GPS position relative to the earth, then it will slam into the side of the car.

lekh2003
Gold Member
It really depends how the drone's navigation system determines "hover." If it keeps the same GPS position relative to the earth, then it will slam into the side of the car.
I'm quite sure that drones define hover as a constant height. Maintaining position to that level of accuracy would be extremely difficult and battery consuming.

olivermsun
Like I said, it depends on the drone's navigation system. If you're talking about relatively simple/inexpensive drones, then sure, a reasonable "hover" would be to maintain a constant height at whatever drift was there when you set it.

A.T.
But if it’s in a moving car, would it move with the car?
If it only uses inertial sensors to navigate, it would move with a car that drives at constant speed and direction, but not if those change.

Some drones use visual sensors to navigate:
https://www.dronezon.com/drone-reviews/drone-gps-autopilot-at-very-affordable-prices/

The Mavic uses 4 Vision Sensors which sees in front and below whether you are on a cliff or in a forest. These vision sensors also work indoors giving it the smoothest flying and hovering of any drone to date.

Such a drone might try to follow the cars accelerations too.

Drakkith
Staff Emeritus